News - UMD Physics

Maryland Quantum-Thermodynamics Hub Launches With $2M Grant

Details: Category: Department News; Published: Friday, September 30 2022 00:01

The Maryland Quantum-Thermodynamics Hub, supported by a grant from the Templeton Foundation, will bring together researchers from several universities to galvanize a field that is central to understanding the workings of our universe and to developing robust quantum technologies, ranging from a new class of computers to secure communications networks. It will be based in the Institute for Physical Science and Technology at UMD.

Leading the project at UMD are Christopher Jarzynski, a Distinguished University Professor with appointments in chemistry and biochemistry and in physics, and Nicole Yunger Halpern, a fellow in the Joint Center for Quantum Information and Computer Science (QuICS) and a scientist at the National Institute of Standards and Technology.

“We’re delighted at the support that UMD institutions, including IPST, have demonstrated for establishing this hub and for quantum thermodynamics in general,” said Yunger Halpern. “We look forward to building a North American lodestone for quantum thermodynamics, inspired by our international peers.”

[Mapping the Quantum Frontier: UMD Expands Its Footprint as the ‘Capital of Quantum’]

In the quantum world, you don’t need to just think about the movement of energy and particles—as in traditional thermodynamics—but also about the movement of information in uniquely quantum ways. The thermodynamic rules of quantum systems require significant additional research before physicists can understand them as well as they do the established laws of thermodynamics that govern heat flow in things like refrigerators, steam engines and rocket thrusters.

The Maryland hub team is not scrapping traditional thermodynamics completely, however. Instead, it is combining physicists’ established understanding with the modern tools of quantum physics and information processing to develop deeper insights.

The scientists involved in the Maryland Quantum-Thermodynamics Hub say they’re not only interested in a richer understanding of quantum physics and its use in technology, but also how it connects to the flow of time and the laws of classical physics we constantly see playing out in everyday life.

In addition to cutting-edge research, the hub team also plans to organize symposia, seminars, an international conference, a visitors program and a science-fiction short-story contest.

In addition to Jarzynski and Yunger Halpern, senior personnel involved include University of Maryland, Baltimore County Associate Professor of Physics Sebastian Deffner; UMD Assistant Research Scientist Luis Pedro García-Pintos, who is also a member of the Joint Quantum Institute and QuICS; University College Dublin Assistant Professor Steve Campbell; University of Southern California Quantum Information Scientist Amir Kalev, who was formerly a Hartree postdoctoral fellow at QuICS; and Arizona State University Assistant Professor Kanu Sinha, Ph.D. ’15.

Story by Bailey Bedford

Read a blog post on the establishment of the hub by Nicole Yunger Halpern, or Maryland Today’s previous story on her recent book on the field of quantum steampunk.

Quantum Gases Keep Their Cool, Prompting New Mysteries

Details: Category: Research News; Published: Tuesday, September 27 2022 02:46

Quantum physics is a notorious rule-breaker. For example, it makes the classical laws of thermodynamics, which describe how heat and energy move around, look more like guidelines than ironclad natural laws.

In some experiments, a quantum object can keep its cool despite sitting next to something hot that is steadily releasing energy. It’s similar to reaching into the oven for a hot pan without a mitt and having your hand remain comfortably cool.

For an isolated quantum object, like a single atom, physicists have a good idea why this behavior sometimes happens. But many researchers suspected that any time several quantum objects got together and started bumping into each other the resulting gang of quantum particles would be too disorganized to pull off this particular violation of the laws of thermodynamics.

A new experiment led by David Weld, an associate professor of physics at the University of California, Santa Barbara (UCSB), in collaboration with Professor Victor Galitski of the Joint Quantum Institute, shows that several interacting quantum particles can also keep their cool—at least for a time. In a paper(link is external) published Sept. 26, 2022 in the journal Nature Physics, Galitski, who is also a Chesapeake Chair Professor of Theoretical Physics in the Department of Physics at UMD, and the researchers at UCSB describe the experiment, which is the first to explore this behavior, called dynamical localization, with interactions included.

The experiment builds on theoretical predictions made by Galitski and his colleagues, and the results reveal mysteries for the researchers to pursue concerning what the particles are doing in the experiment. Uncovering exactly how the particles can break a revered law of thermodynamics might provide significant insight into how quantum effects and interactions combine—and those insights might find uses in the designs of quantum computers, which will necessarily contain many interacting particles.Equipment at the University of California, Santa Barbara used to create clouds of Lithium atoms. It was used to study how atoms absorb energy when they have various levels of interaction with each other. (Credit: Tony Mastres, UCSB)

“The big question is whether this phenomenon can survive in systems which are actually of interest,” Galitski says. “This is the first exploration of the fate of this very interesting phenomenon of non-heating as a function of interactions.”

For a single particle, physicists have the math to explain how quantum mechanical waves of probability sway and crash together in just the right way that crests and troughs meet and cancel out any possibility of the particle absorbing energy. Galitski and his colleagues decided to tackle the more complicated case of investigating if the same behavior can occurs when multiple particles interact. They predicted that in the right circumstances repeated kicks of energy would warm up the collection of particles but that at a certain point the temperature would plateau and refuse to go up anymore.

The next natural step was to confirm that this behavior can happen in a lab and that their math wasn’t missing some crucial detail of reality. Fortunately, the idea intrigued Weld, who had the right experimental equipment for testing the theory—almost. His lab can set up quantum particles with the needed interactions and supply of energy to attempt to defy thermodynamics; they used lasers to trap a quantum gas of lithium atoms and then steadily pumped energy at the atoms with laser pulses.

But there was a catch: To keep the math manageable, Galitski’s theory was calculated for particles confined to live on a one-dimensional line, and it’s not easy for Weld and his team to keep the cloud of atoms that tightly constrained. Atoms in a gas naturally explore and interact in three dimensions even when confined in a slender trap. The team made their cloud of atoms long and narrow, but the extra wiggle room tends to significantly impact the quantum world of atoms.

“With just a few discussions, the basic picture of what we wanted to do was clear quite quickly,” Weld says. “Though the experiment turned out to be quite challenging and it took a lot of effort in the lab to make it all work!"

While Weld’s lab couldn’t do the experiment in one dimension, they could easily control how strong the interactions were between atoms. So, the team started with the well-understood case where particles weren’t interacting and then observed how things changed as they increased the interaction strength.

“So, they didn't actually do exactly what we wanted them to do, in a one-dimensional system, because they just don't have one-dimensional systems,” Galitski says, “but they did what they could do. There is this kind of a tension, which is common, that what’s easy theoretically is usually difficult experimentally, and vice versa.”

When the particles weren’t interacting, the researchers saw the expected result: the particles heating up a little before reaching a constant temperature. Then, when they adjusted the experiment so that the atoms could interact a little, they still saw the temperature plateau at the same level. But unlike in the one dimensional theory, the atoms eventually started heating up again—although not as quickly as predicted by normal thermodynamics. When they increased the level of interactions, the temperature plateaued for a shorter time.

While Galitski’s one-dimensional theory doesn’t describe the exact experiment performed, another theory seems to have some luck explaining the sluggish heating that follows the plateaus. That theory applies to very cold groups of particles that have formed a Bose Einstein condensate, a phase of matter where all the particles share the same quantum state. The equations that describe Bose-Einstein condensates can predict the rate of the slow heating—despite that very heating meaning that the atoms shouldn’t be describable as a Bose Einstein condensate.

“So, in some sense, it's a double mystery,” Galitski says. “We actually don't know why it goes this way, but there is a theory which is not supposed to work but kind of works.”

The observed plateaus prove that interactions don’t always force particles to bow to the decrees of thermodynamics. Efforts to push experiments to test the predictions for particles constrained to one dimension and to push the theory to explain the three-dimensional experiments might not only reveal new quantum physics but could also lead to the development of new research tools. If the physics behind these experiments can be untangled, perhaps the plateaus will one day be extended and can be used to design new and better quantum technologies.

“Mysteries are always good because they lead oftentimes to new discoveries,” Galitski says. “What would be nice is to see whether you can stabilize the dynamic localization—this plateau—under some protocols and conditions. That's what they're working on. And it's important because it would preserve quantum information.”

In addition to Galitski and Weld, former UCSB physics student Alec Cao; UCSB graduate students Roshan Sajjad, Ethan Q. Simmons, Jeremy L. Tanlimco and Eber Nolasco-Martinez; former UCSB postdoctoral researcher Hector Mas; and UCSB postdoctoral researchers Toshihiko Shimasaki and H. Esat Kondakci were also co-authors of the paper.

Original story by Bailey Bedford: https://jqi.umd.edu/news/quantum-gases-keep-their-cool-prompting-new-mysteries

Beyond Higgs: The Search for New Particles That Could Solve Mysteries of the Universe

Details: Category: Research News; Published: Wednesday, September 07 2022 00:01

An elusive elementary particle called the Higgs boson is partly to thank for life as we know it. No other elementary particles in the early universe had mass until they interacted with a field associated with the Higgs boson, enabling the emergence of planets, stars and—billions of years later—us.

Despite its cosmic importance, scientists couldn’t prove the Higgs boson even existed until 2012, when they smashed protons together at the most powerful particle accelerator ever built: the Large Hadron Collider (LHC). A decade later, this massive machine, built in a tunnel beneath the France-Switzerland border, is up and running again after a series of upgrades.

As the search for new particles starts anew, researchers like Assistant Professor of Physics Manuel Franco Sevilla find themselves wondering if they will discover anything beyond Higgs.UMD Assistant Professor of Physics Manuel Franco Sevilla is helping to upgrade the Large Hadron Collider (LHC) at CERN in Switzerland. In the above photo, he is shining a light on silicon sensors to measure whether their dark current increases—a sign that they are properly connected. Photo courtesy of Manuel Franco Sevilla.

“It’s a tough question because particle physics is at a juncture,” said Franco Sevilla, who is working at the LHC this semester. “It’s possible that we are currently in what physicists call a ‘nightmare scenario,’ where we discovered the Higgs, but after that, there’s a big desert. According to this theory, we will not be able to find anything new with our current technology.”

This is the worst-case scenario, but not the only possible outcome. Some scientists say the LHC could make another discovery on par with the Higgs boson, potentially identifying new particles that explain the origin of dark matter or the mysterious lack of antimatter throughout the universe. Others say new colliders—more powerful and precise than their predecessors—must be built to bring the field into a new era.

There are no easy answers, but Franco Sevilla and several other faculty members in UMD’s Department of Physics are rising to the challenge. Some are working directly with the LHC and future collider proposals, while others are developing theories that could solve life’s biggest mysteries. All of them, in their own way, are advancing the ever-changing field of particle physics.

Looking For Beauty

As Franco Sevilla will tell you, there’s beauty all around—if you know where to look. He is one of the researchers who uses the LHC’s high-powered collisions to study a particle called the beauty quark—b quark for short. It’s one of the components of “flavor physics,” which observes the interactions between six “flavors,” or varieties, of elementary particles called quarks and leptons.

Because these particles sometimes behave in unexpected ways, Franco Sevilla believes that flavor physics might lead to breakthroughs that justify future studies in this field—and possibly even the need for a new particle collider.

“Some of the most promising things that will break the ‘nightmare scenario’ and allow us to find something are coming from flavor physics,” he said. “We still haven't fully discovered something new, but we have a number of hints, including the famous ‘b anomalies.’”

These anomalies are instances where the b quark decayed differently than predicted by the Standard Model, the prevailing theory of particle physics. This suggests that something might exist beyond this model—which, ever since the 1970s, has helped explain the fundamental particles and forces that shape our world.

Some mysteries remain, though. Physicists still don’t know the origin of dark matter—an enigmatic substance that exerts a gravitational force on visible matter—or why there’s so much matter and so little antimatter in the universe.

Sarah Eno, a UMD physics professor who has conducted research at particle accelerators around the world, including the LHC, said these answers will only come from collider experiments.Sarah Eno, a physics professor at UMD, sits atop a model of a Large Hadron Collider (LHC) dipole magnet at CERN about 10 years ago. At the time, she was participating in LHC experiments and frequently spent her summers at the lab in Switzerland. Credit: Meenakshi Narain.
“What is the nature of dark matter? Nobody has any idea,” Eno said. “We know it interacts via gravity, but we don’t know whether it has any other kinds of interactions. And only an accelerator can tell us that.”

Better, Faster, Stronger

After the third (and current) run of the LHC ends, the collider’s accelerator will be upgraded in 2029 to “crank up the performance,” according to the European Organization for Nuclear Research (CERN), which houses the collider.

With the added benefit of stronger magnets and higher-intensity beams, this final round of experiments could be a game-changer. But once that ends, Eno said the LHC will have reached its limit in terms of energy output, lowering the odds of any new discoveries. The logical next step, she said, would be to construct a new collider capable of propelling the field of particle physics forward.

“The field is now trying to decide what the next machine is,” Eno said.

Around the globe, there are various proposals on the table. There is a significant push for another proton collider in the same vein as the LHC, except bigger and more powerful. Electron-positron colliders—both linear and circular in shape—have also been proposed in China, Japan and Switzerland.

Eno is one of the physicists leading the charge for the construction of an electron-positron collider at CERN. It would be the first stage of the proposed Future Circular Collider (FCC), which would be four times longer than the LHC. By the late 2050s, it would be upgraded to a proton collider, with an energy capacity roughly seven times that of the LHC. Eno, who was appointed one of the U.S. representatives for this project, said the electron-positron collider would allow physicists to study the Higgs boson with significantly higher precision.

“When an electron and positron annihilate, all their energy becomes new states of matter,” Eno said. “This means that when you’re trying to reconstruct the final state, you know the total energy of that final state. This allows you to do much more precise measurements.”

This proposal does come with some challenges. Circular colliders radiate off a lot of energy, making it difficult to accelerate electrons to high energy. Eno said this can be avoided by building a massive collider with a long tunnel (to the tune of 62 miles, in the case of the FCC), preventing electrons from losing steam as they whip around sharp corners.

The radiation problem has pushed some physicists towards another theoretical possibility: a muon collider. Muons are subatomic particles that are like electrons, but 207 times heavier, which keeps them from radiating as much. This would make them ideal candidates for collider research—if only they didn’t decay in 2.2 microseconds.

“If you talk to the muon collider proponents, their faces light up because it’s such a challenge,” Eno said. “And who doesn’t like a challenge?”

Clean Collisions

One of Eno’s colleagues at UMD—Distinguished University Professor and theoretical physicist Raman Sundrum—endorses the muon collider idea. So much so that he and a team of physicists wrote a paper titled “The muon smasher’s guide,” which appeared in Reports on Progress in Physics in July 2022.

“We build colliders not to confirm what we already know, but to explore what we do not,” the research team wrote in their paper. “In the wake of the Higgs boson’s discovery, the question is not whether to build another collider, but which collider to build.”

They made the case for the world’s first muon smasher, arguing that these collisions would be “far cleaner” than proton collisions, which occur at the LHC. Unlike protons—a composite object made of quarks and gluons—muons are elementary particles with no smaller components. This would let physicists see only what they want to see, without any distractions.

“Muon collisions would make it easier to diagnose what’s going on,” Sundrum said. “When something extraordinary happens, it doesn’t get dwarfed by all of the mundane crashing of many parts.”

Considering that the Higgs boson only appears once in about a billion collisions at the LHC, this level of clarity and precision could make a world of difference. However, the more the field of particle physics advances, the more challenging it is to find something new.

“The Higgs was a needle in the haystack, but discovering newer particles could be even subtler and harder,” Sundrum said.Artistic rendering of the Higgs field. Credit: CERN

Despite these challenges, the LHC could still make a major discovery. Sundrum continues to develop theories that guide and inspire the field, including the idea that the LHC could find a “parent particle” that gave rise to all protons in the universe. If this comes to fruition, it would be worth building new colliders that could validate the LHC’s initial findings and provide a more complete picture of why matter dominates over antimatter in the universe, Sundrum said.

In the coming years and decades, physicists will continue to debate the pros and cons of various collider proposals. The outcome will depend partly on scientific advancements, and partly on political will and funding. Sundrum said it’s not cheap to build a collider—with some projects expected to cost $10 billion—but the discoveries that could come from these experiments are priceless.

“An enormous number of people find it very moving and interesting to know what it’s all about, in terms of where the universe came from, what it means and how the laws work,” Sundrum said. “Individually these experiments are expensive, but as a planet, I think we can easily afford to do it.”

Written by Emily Nunez

From Unexpected Opportunity to Game-changing Discovery

Details: Category: Department News; Published: Tuesday, September 06 2022 00:01

In the world of startups, opportunity can come knocking in strange ways. Six years ago, Didier Depireux (Ph.D. ’91, physics) was doing research at the University of Maryland when he was approached by Sam Owen, a young scientist who said he’d developed a device to treat motion sickness. Depireux was skeptical but decided to check it out.

“Since I get very severe motion sickness, I made a deal with him,” Depireux recalled. “I said, ‘I’ll come over with my car and you can drive me around while I use the device. If I haven’t thrown up after 20 minutes while I’m in the back of the car reading, I’ll join the effort.’”

The two made plans to meet in Washington, D.C., on a muggy July afternoon. Didier Depireux

“So, I go to Georgetown. The windows are down, it’s hot, it’s humid and I’m thinking I will not make it past the first turn,” Depireux explained. “Owen is driving and I’m in the back seat using his device and reading my cellphone. And for the first time in my life—and I’m over 50 years old—I was able to read in the back of a car and not get sick. I thought, ‘I need to join this, this is amazing.’”

Thanks to that strange summer ride-along, Depireux joined Owen in launching a startup called Otolith Labs to address inner ear-related conditions and their often debilitating symptoms. Otolith’s noninvasive vestibular system masking technology—designed for acute treatment of vestibular vertigo—received the FDA’s Breakthrough Device designation and clinical trials are ongoing, with support from investors including AOL founder Jack Davies and billionaire entrepreneur Mark Cuban.

All of this sets the stage for a major test that could lead to the startup’s ultimate goal—FDA approval as early as next year.

“In July we told the FDA we want to do a large-scale pivotal trial with hundreds of participants,” Depireux explained. “If all goes well, we’ll have a meeting next summer where the FDA will approve us and then the device will become available.”

For Depireux, it’s the latest step on a bigger mission that has guided his career.

Didier Depireux“It’s mostly relevance,” he explained. “I would like my life to make a difference, that’s the one thing that keeps me going.”

From philosophy to physics

Depireux was raised in Belgium. A bright, thoughtful boy, he grew up with a strong interest in science and theory, thanks to his father, a physics professor, and his mother, a chemistry teacher.

“I was always very science-y,” Depireux recalled. “Initially, I wanted to become a philosopher and I read this 800-page book—I think it was Kant—and at the end of it I was like, ‘I still don’t know the answer, and I’m not even sure I understand the question anymore.’ That’s when I thought that’s not a good fit for me.”

Depireux eventually gravitated toward physics. After receiving his B.S. in physics from the University of Liège in Belgium in 1986, he began his graduate work in physics at the University of Maryland, where he focused on string theory and met Distinguished University Professor of Physics Sylvester James Gates Jr., who quickly became a mentor and friend.

“Jim had a huge impact on me. He was a fantastic person to work with and he had so much positive energy,” Depireux said. “I still remember late one night I was working on something, and I was stuck and I wrote to him, and he said, ‘I’ll come over, let’s work this out.’ So we had office hours at 10:30 p.m. just because I couldn’t solve a problem.”

Depireux earned his Ph.D. in 1991 and went on to do postdoctoral work in Quebec, Canada, before returning to College Park in 1994. Inspired by his wife Pamela, who was getting her Ph.D. in neuropharmacology, Depireux took on the challenge of modeling the brain and studying how it processes sound. By 2001, he was also teaching a gross anatomy class at the University of Maryland School of Medicine.

“I think, to this day, I am the only string theorist who has taught gross anatomy,” he reflected.

From his research on the brain and hearing, Depireux shifted his focus to tinnitus—disruptive ringing in the ears. He explored possible treatments and eventually teamed up with former UMD Bioengineering Professor Benjamin Shapiro who was already working on the drug delivery challenges Depireux was trying to solve.

“I wanted to get drug delivery to the ear but I didn’t know how to do it,” Depireux said. “He had this method with nanoparticles to deliver drugs and I had the target so we started working together.”

In 2013, the two launched Otomagnetics, a startup that has made major strides in developing noninvasive methods to treat inner ear diseases and more.

“We’ve gotten very nice results as far as drug delivery goes and Otomagnetics is still an ongoing concern,” Depireux explained, “But raising money for drug delivery is the real challenge, because to get drug delivery to the ear is going to take hundreds of millions of dollars, and that hasn’t happened yet.”

Going all-in on Otolith

Depireux balanced his time between Otomagnetics, his UMD research and teaching at the School of Medicine until 2016, when he experienced Owen’s experimental motion sickness device for the first time. Depireux saw so much potential with the device that he went all-in on Otolith.

“You have to have pretty strong resilience to join a startup—I went for a year and a half without a salary or anything,” Depireux explained. “It’s not like we didn’t have money, we just needed all of the money to develop the device, get the patents in, all of the things we had to do.”

Though Otolith started with a motion sickness device, its co-founders hoped to make an even bigger impact by developing a device for vertigo, debilitating dizziness often caused by problems in the inner ear.

And they had a plan.

“For tinnitus or ringing in the ears, some patients get relief from a noise masker—they can still perceive their tinnitus, but the noise masker allows them to ignore the tinnitus,” Depireux explained. “So Sam, my cofounder said, ‘Why don’t we come up with a noise masker for the vestibular system?’”

That’s exactly what they did. Their novel device, worn like a headband, treats vertigo by applying localized mechanical stimulation to the vestibular system through calibrated vibrations.

Depireux says he never would have made it this far without physics.

“My physics training really helped me,” he explained. “In physics, you have this huge problem and you have to break it down. If it’s intractable, you make it tractable, break it into small, simple things we can understand and then we can solve it.”

Promising results and personal stories

Clinical trials of Otolith’s investigational headband have yielded promising results. In the first of a series of ongoing clinical studies, 87.5% of the 40 participants reported a reduction in their vertigo within five minutes of turning on the device. But for Depireux, it’s the personal stories that are most rewarding.

“Somehow my phone number was listed as an emergency contact on clinicaltrials.gov, which I thought would be for emergencies only,” he said. “I’d have patients calling me in tears, telling me, ‘When my grandkids visit, I can finally bend down and pick them up, and it used to be that just bending down would send me into such vertigo that I would have to go to bed for days.’ Or ‘For the first time in years, I’ve been able to walk around the block.’ That’s what really motivates me.”

It's been Depireux’s goal all along—doing relevant research that changes people’s lives.

“We cannot help 100% of vertigo patients, no device does that,” he reflected. “But if we can help even half of those patients, that’s really my hope.”

Looking back on a career path that’s been anything but predictable, Depireux appreciates every challenge and setback that got him to where he is today.

“Something can feel like a failure when things go wrong, but then later you realize you really learned something from it,” he reflected. “I’m so grateful I was given the opportunity to come to the U.S. and study physics and do research in College Park, do this random walk in my career and finally end up doing something that I feel has given me great meaning in my life.”

Written by Leslie Miller

Maryland Quantum-Thermodynamics Hub Launches With $2M Grant

Quantum Gases Keep Their Cool, Prompting New Mysteries

Beyond Higgs: The Search for New Particles That Could Solve Mysteries of the Universe

From Unexpected Opportunity to Game-changing Discovery

More Articles ...

College and University Links

Department of Physics

Information